Endless tread drive for tractors



Feb. 13, l951 y G. B. slr-IERMAN AET AL 541494-3- ENDLEss TREAD DRIVE'FOR TRAcToRs Filed Nov. 11, 1944 v 4 sheets-sheet 1 www ff G. B. SHERMANET AL ENDLESS TREAD DRIVE FOR TRACTORS Feb. 13, 1951' -4 Sheevhs-Sheet 2Filed Nov; 11, 1944 .QQMVOO- G. B. SHERMAN ET AL -ENDLEss TREAD DRIVEFOR TRAqToRs Feb. 13, 1951 4 Sheets-Sheet 3 Filed Nov. 11, 1944 G. B.SHERMAN ET AL ENDLESS TREAD DRIVE FOR TRACTORS Feb. 13, 1951 4Sheets-Sheet 4 Filed NOV. 11, 1944 Patented Feb. 13, r1951 ENDLESS TREADDRIVE FOR TRACTOR George B. Sherman and Hubert M. Clark, Detroit, Mich.,assignors, by mesne assignments, to Sherman Industries, Inc., acorporation of Delaware Application November 11, 1944, Serial No.562,964

13 claims. (ci. 18o-'9.1)

This invention relates to tractor and more particularly to tractors forgeneral agricultural purposes.

The large majority of farms today are farmed with horses despite thefact that tractors have been known and available for many years. This islargely because tractors as heretofore known have not been abel tooperate to advantage in small or irregularly shaped fields or where theground is hilly or over soft, sandy, orwet soil or soil which is hardorfull of obstructions. Due yto the manner of connecting implements to thetractors shifting of weight from the front to the rear of the tractoroccurs in use and this, togethzer with the high center of gravityresulting from thef-necessary cultivating clearance, makes the tractorsunsafe under many operating conditions.

.Tocompensate for shifting of weight the tractors have been made heavierand this increases their cost and makes them difficult to operate.

' It is the principal object'of the present invention to provide atractor which overcomes these 1 objections and which can operateeffectively under adverse conditions To this end the invention providesa tractor which is smaller and has less parts and is therefore lessexpensive than Y tractors heretofore known, which has a low centier ofgravity while maintaining adequate cultiyatingclearance, whichissubstantially impossible to tip over so that it is safe, which can beoperated with a minimum of physical effort and maximum comfort, whichprovides a maximum drawbar pull with minimum weight, and in which therevis a minimum shifting of weight from .front to rear o f the tractor inoperation.

Another object is to provide a tractor which vhas a tricycle suspensionformed by a front driving unit and laterally spaced steerable Wheels atf the rear.

Still another object is to provide a tractor in which the drive is thrua unit-l including a driving V wheel and a pair of bogie wheels aroundwhich an jendless track is supported. The drive unit preferably includesa spring suspension for the front bogie wheel so arranged that the frontwheel normally carries the major part of the weight on the unit, whichis preferably mounted to exert a substantiallyconstant force against theground in all positions and which is moved in a path such as to maintainthe track length around the wheels substantially constant.

A further object of the invention is to provide a tractor in whichlaterally spaced wheels are carried by substantially horizontalfpivotedarms so that the lateral space between the wheels can .sprocket wheel I6which is mounted A still further object is to provide a tractor in whichlaterally spaced wheels are connected to ya steering linkage so arrangedas to maintain the wheels substantially parallel in any laterallyadjusted position thereof. l

A still further object is to .provide a tractor including a powertakeoff connected to the en;- gine separately from the tractor drivingunit. In one preferred construction, the driving unit is connected tothe engine shaft at one end of ythe engine and the power takeoff isconnected to the opposite end of the engine shaft.

The above and other objects and advantagesof the invention have beenmore readily apparent from the following description, when read inconnection with the accompanying drawing, in

Which- Figure 1 is a side elevation of a tractor embodying theinvention; Figure 2 is a top plan view; t

Figure 3 is an enlarged side elevation of the driving unit of Figure 1;Figure 4 is a partial section on the line ofvFigure 3; and

Figure 5 is a view similar to Figure 3 of an alternative construction.

The tractor as best seen in Figures 1 and 2, comprises `a main frame Ion which an engine indicated generally at Il is mounted. As seeninFigure 1, the engine is mounted intermediate the ends of the frame andis provided with a cooling -radiator behind the grill l2 at the .forwardend of the engine and with a fuel supply tank AI3 overlying the engine.The grill i2 forms a sup-- port for the back of an operators seatindicated at I4. 'yf

The frame is suspended on a front drive unit indicated generally at l5and which is constructf ed as best seen in Figure 3. .As shownin'thisfigure, the drive unit includes a driving i or on an 'axle l1 journalledon the main frame l0. The wheel I6 is driven from the engine thru abevel pinion or the like indicated at I3 which is connectedV to theengine thru the usual clutch and transmis,"- sion mechanism. Since theclutch and trans.-v

mission may be standard parts' they are not 2G of the frame vIll on anaxis xed relative to f the frame. Between the driving Wheel and the-rear bogie wheel, a supporting arm 2l is pivoted on the" frameextension 20 and extends forwardly therefrom. As shown in Figure 3, thearm 2| is formed at its end with a split collar portion engaging aneccentric 22 on a supporting shaft Whose ends are journalled in bosses23 on the frame. By turning the eccentric 22 in the end of the arm 2lthe .effective length of the 'arm can easily beadjuslted to tighten orloosen the track described later. At its forward end, the arm 2| carriesa, front bogie wheel 24 which lies below and in front of the drivingwheel l 6 fin endless track 25 which may be of any desired construe#Ition, such, for example, as molded rubber'or the like reinforced bylongitudinally extending cables, fits around the several wheels. WhentheV driving or sprocket wheel is turning, it will drive the track whichrides over and is held .against the ground by the bogie wheels I9 and24.

The arm 2| is urged downwardly aboutits'pivot to press the bogie wheel24 against the ground by spring means as shown more particularly inFigure 4;. ""As shownin this iigure,..a pairoftele- 'scopic'ally'interengaged guide 'members 26 :are ciinectedY at their lower ends thruball and socket joints to the arm 2| and 'a't'theirupper `endstos'iinilarY joints "to spaced points onthe frame. l0. Compression springs2l vare fitted around .the guide members 26 and act therethru to urgethe `VaLl-1112i 'l downwardly Vrelative 'to the frame. It will benotedthat the guide members and springs le at an angle 'to each other'so that the downward component of the force exerted thereby on the arm2l 'decreases as 'the Varm rises. Since raising of "the arm compressesthe springs and increase the 'force exerted thereby the changingangle'of the springs "may be made to compensate substantially exactlyfor the spring increase .so that the downward force on the'arm2l will besubstantially constant in all positions 'ofthe arm. With thisconstruction, the loading on. the `front bo'gie wheel and on theirontpart of the vtrack may be kept substantiallyconstant Yunder "alloperating conditions.

According to one feature of the invention the springs 2 are soselectedandarranged that the major portion of the total 'load ion the driving-iinit will .be carried .'by..the...front..bogie wheel. Sinethe trackis...forrne d withjc1eatsor-lrough- .e'nedaportion to. improve its grinagainst the ground this arrangementprpvides. .for .loadinetheiorwardrportion. of .the track, where itnst. .en-

gages the ground .to the. maximum extentsothat the.gripsonthetrack Willbe lledto provide the.. maximum. trative.. eiect. A s the track movestoward the .rear bogie wheel it. wilrmaintain its grip against theground with a lesserde- :grae .of .pressure so that` bxloadins.theirward portonof the track to the maximum extent, the maximumtr'active engagement with the ground isprovided.

It wl1 be lnoted from the arrangelr lentof,` Fig- ,ure..`3, .that thepivotal position of the arm 2l is so.-s.e1 ected that Aas in moveseboutits Pivo.t in response to uneven ground condition s, it will travel inan arcuate path such that the total length of the. track aroundl theseveral. ivl'ie els ,remains substantially constant.v With this arvmvdedbetween the front and vrearubogiesgjf .desired `to hold the bottom' partofthe track against, the ground throughout its length.,

the arrangement of the driving unit to 'carry the major portion of theload on the front bogie 4. wheel improves the steering. Since therearward portion of the driving unit is loaded relatively lightly, itcan slip sideways without material resistance while the forward portionof the unit remains in firm contact with the ground.

Thispermits 'the"unit""to' turn readily without interfering with itstractive grip on the ground. ".n alternative driving unit is illustratedin ligure .5 in which both the front and rear bogie wheels areresiliently supported on the frame. In

this construction the driving wheel 28 is connecte d to 'the engine thrua driving pinion 29.

The'rearbogiewheel 3G is supported on an arm 3l which is 'pivoted to theframe at 32 and which is urgedidownwargllyby one or more compressionsprings 33. The forward bogie wheel 34 is carried by an arm 35 which ispivoted to the frame at 36 between the driving wheel and the rear."ibogie wheel. compression 'spring 731 which'iiiay be arranged 'as 'moreparticularly shown in Figure 4 urges the arm 35 downward.

The pivotpjint's for lthe arms '3| and'35 areiso selected "that the `bogie""wheels may move simultaneously lt hru"'a'limited range without`tending to"s`tr`et `:h`the4 endless' 'track 38 Which'eXtendS around'the bogie wheels and the "driving wheel.

In this lt'oristruction"as in that "of VFigure?,

springsi3l are-'preferablys'tilerthan the springs 33' so that the majorportion of the vweightl on the 'driving unit will "becarried bythevrfront `vTherear"end of thetractor is supportedon ally spaced 'steerable'wheels v'39 whichrare the wheelsSl andfinay beheld ina-cljuste'dposition `witlfa-nyI desired V:space between the" wheels.

a d 'are adapted to b" e `r connected 'at their outer fitting 'thruYselected onefoffafseries "of holes 7.. 4 in the farms With thisconstruction, "the `between the'rlearwheels`39 lcaneasily/'loe 'thedesired positioniand A'locking them inplace pur o ejtleyfare supportedon v"vertical at heffouter ends `'ofj'the arms "49.

arev secured to the wheel pivots s and I` vvas *shown extend EindlyAfrom thewhelpivots.

tlas warte-app more, due to the arrangement'ofthelvers 68, 76 link 41and arms 46, when the arms 40 are A.timings :movedto 'separate thewheels, the links 41 will :be placed under tension andwill' turnthewheels '35hy By properly proportioning the lengths of the levers 138 andarms, 46, this turning can be vmade such asA to maintain the wheels 39sub- 'stantially parallel in all. adjusted positions. Therefore, theonly operation necessary to vary the spacing between Vthe wheels 39 isto move the `arms 4i! to the desired position and lock them in place bymeansA of the links 42, the direction of the wheels being automaticallyadjusted thru the steering linkage. Y

fl The tractor is adapted to be connected to an limplement or otherdesired type of load thru a 'head unit indicated generally at 54 Vwhichmay be offthe type more particularly'described and :claimed in theapplication of George B. Sherman, ySerial No. 447,341 filed June 17,1942, which became Patent No. 2,394,210, February 5, 1946. The unit 54may carry a leveling mechanism operated Aby shaft 55 andv crank 56 tolevel the implement :and may operate automatically as described in saidSherman application to maintain the implement at the proper depth in theground. Adjust- Iment of the control unit to vary the implement depthandto raise the implement for turning may ;be accomplished from Aadjacent4the drivers seat thru control levers 5l. The tractor engine speed maysimilarly be controlled thru a throttle lever pilla-, the-transmissionthru a shift lever 51D and the clutch vthru a pedal 5'ic.

j, For many purposes it is desirable to provide a power take offwhich-may be used in connection rwith the implements connected to thetractor or for utilizing the tractor as a stationery power plant. Forthis purpose a power take off shaft 58 is carried'by and projects fromthe rear end of the .engineas seen in Figure 1. The shaft 58 isconnectedk to 'the engine thru a clutch'59 which may be controlled by alever 65. rangement,`fzit will be noted thaty the shaft 58 canbedrivencontinuously whether or not the tractoris in motion. This is desirablefor oper- ,-.ating many types of machines such as power `driven mowersso that the cutting mechanism ofthe mower maycontinue to cut even thoughthe tractor is slowed down or stopped. Since the ,'-power take oi' shaft58 and its clutch 59 are at the opposite -end of' the engine from theconnection to the driving unit, the take off shaft may be controlled'andoperated independently of the 'id rving unit. v i

In operating the tractoritwill be noted `that 2. the weight of thevoperatorand a ksubstantial porf' tion of the weight ofthe frame andengine are carried bythe front driving unit. Since the trac- -,tiveeffect vcornes from the front portion of the tractonfthe' weightAdistribution! is affected very little bythe tractive pull of a loadconnected to the head 54 and it is'alsoaffected to a very minor=extent-by varying contour of the ground over which the tractor isoperated. Thus the weight pressing the driving unit against the groundis substantially constant under all conditions of operation. Thisprovides a tractor which is very exible in its uses and which is able tooperate in places and under conditions in which a conventional tractorcan operate only inefciently, if at all. Thus an extremely exibletractor is provided which is able to perform a wide variety ofoperations under widely varying conditions.

While `one embodiment of the invention has been shown and described indetail herein, it will be understood that this is illustrative only and,is not intended as a definition of the scope of With this ar-y 6 theinvention, reference being had for this purpose to the appended claims.

What is claimed is:

1. A tractor comprising a frame, an engine on the frame, a pair ofsteerable wheels adjacent one end of the frame, and a driving unitadjacent the other end of the frame, the driving unit including, adriving wheel on the frame above the bottom thereof,vmeans for drivablyconnecting the ydriving wheel to the engine, front and rear bogie wheelsbelow the driving wheel, an arm pivoted to the frame between the driving'wheel and the rear bogie wheel on which the bottom thereof, means fordrivably connecting the driving wheel to the engine, front and rearbogie wheels below the driving wheel, an arm pivoted to the framebetween the driving wheel and the rear bogie wheel on which the frontbogie wheel is mounted, a compression spring acting between the armandthe frame arranged at such an angle that it will exert asubstantially constant downward force on the arm regardless of theposition of the arm, and an endless track around the wheels.

3. A tractor comprising a frame, an engine on ,the frame, a pair ofsteerable wheels adjacent one end of the frame, and a driving unitadjacent the other end of the frame, the driving unit including adriving wheel on the frame, means f or drivably connecting the drivingwheel to the engine, front and rear bogie wheels below the drivingwheel, an endless track around the wheels, and means yieldingly mountingat least the front bogie wheel on the frame and so constructed andarranged that the front bogie wheel normally carries a greater amount of"weight than the rear bogie wheel.

4. A tractor comprising a frame, an engine on l the frame, a pair ofsteerable wheels adjacent one end of the frame, and a driving unitadjacent the'other end of the frame, the driving unit including adrivingk wheel on the frame above the bottom thereof, means for drivablyconnecting Y the driving wheel to the engine, a rear bogie wheel mountedon a fixed axis on the frame below and to the rear of the driving wheel,an arm ,pivoted on the frame between the driving wheel and the j rearbogie wheel, a front bogie wheel carried by the arm below-and to thefront of the driving wheel, spring means urging the arm downward, and anendless track around the wheels.

.5. A tractor comprising a frame, an engine'on fthe frame, a pair ofsteerable wheels adjacent one end of the frame, and a driving unitadjacent the other end of the frame, the driving unit including adriving wheel on the frame above the bottom thereof, means for drivablyconnecting the driving wheel to the engine, a rear bogie wheel mountedon a lixed axis on the frame below and to the rear of the driving wheel,an arm pivoted on the frame between the driving wheel and the rear bogiewheel, a front bogie wheel carried by the arm below and to the front ofthe driving wheel, a pair of compression springs acting between the armand the frame lying at an angle to each other to exert a substantiallyconstant downward force on the arm f'regaless of -fits pivotaifpositiiin, and :endless track around the wheels.

6. A tractor comprising 1'a` fffralmefaniengine on v*oifiefen'dy oftheframegband a'dr-iving unit'adjacent .1'

'the-other endof theframfthe driving runitzr-in- `l cluding adrivingwheel onwthe Vframeabove the Abottom `thereof, means for drvablyconnecting the'driving wheel to thesengine, .-arjpairof. arms:pivotedfto the Hframe j'adjacent the driving wheel .and 'extendingVforwardly and rearwardlyzrespec'- ftively, b'ogie wheelsfcarried by4fthe arms,` "and an :endless `'track around the .drivingxwheel and -thebugie wheels.

57.1A driving unit `for vatracto'i' comprisingza driving wheel adaptedto1bepowerdrivemffront ajridrear` bogie *wheelsv belowrfand tov-the.front 'andirear of the 1 drivingI wheel, z an .armbarr'ying thef-fr'ontrbogie wheel and pivoted-:Jbtwn rthe ivdriving I wheel vand therear bogie .wheel;. an end- :l'e'ss 'trackaro'undl the wheels; and i `aconciloresision spring11u1iging lthe-afm downward :and lying-at sichan'angle that itfzeXets a isubstantia-lly conlstamt vffvoroev'on they armvregardless of A.tlie' pivotal :position: of -theza'frm- 58.4Zi'fidrvingVV unit for a tran'tor. comprising-a V`ving wheel #adapted4tobe powerzdrveniefront Tand fr'ear bog'iey wheels .below l andVVV to,the'. front and lrearfof vvthe ldriving swheel," ifa'n 'Lentllessrtrack.'aound' fthe? wheels; "means :mounting v--thenrear bogie'f-wiiel onanaxis -iiXedirelati-Ve Lto zthe'axis of the driving wheel, and meanslfyieldingly T'Jno'ii'nting -`the fir-ont.-'=b"o'gi`e1V wl'ieel liormovement in' an arcuate pathY abot lia center f-lyin'gl'generarly-between the driving :when .andfithe rear 'Tira-me, aidrlvingwheelmounted fnni,the':rame;-; @pair of 'bo'gie iwheelsbelow-zandonfopposite x-sid'es of theA driving wneel,:fanendlesszitrackaaroun -thewheel, and means'fmountingione1ofv ',-th'ehogie "wheelsfor-arcuatezmovement. aboutaa .center Llying between- Lthe driving wheeland the; `other bogiewheeltoinaintainthe total distanceariozmd tne.thre'e wheels `substa'n'tiallyfeonsta'nt.

I 12. LA @driving nunitlfor. a.v tractor. :.comprisi.ng-,aaV :Lframefa@driving-wheel .mountedz-onr1the frame, la "pair-fof. bogie :wheelsbelow land on opposite sides hof the driving wheel,.-ainfenlessvtakra'round the-"i-wleels, :means: mounting .zones-:of the:bogiewHeelsforzarcuatefmovementSaboutf cerr- :Qterilyin'gbetween`theidrivfingwheekantlLthey other Lb'ogie lwheelto maintaintthexotald-istanceraroun A-tliei- 'three wheels A.substaritiallyg-'iconstan-t,andes Jciorri'lo'rie's`sion s'pri'ng. iaoting L'be'tw'ee'n. the iframe`-andsaidgoriefofitliefloogiexilheelsan ying man fanglefto the p'athfofmovementofzthebogiecvhel fsugc-ihi 'to f'xert y"aslibs'tantiailyeconstantsdown f ward lier-ce on. the'hbo'gie ywheelLre'ga'rdless inflits position.

driving vunitiior laitractor-icomprisingia f fra-me, 1 'a dri-ving`r`wlfie'el mounted Jon-the fra-nie, `-a pair fof boge `#wheels belowfon xfrnopssite sides lof f lthef ldriving Wheel, Lan' i endless z track.REEERENGESvoI'BED YThe'ffollowing references 'rareof :recordlinjgthe"file .of this ipaten't:

